Gaseous fuel powered engines can operate using a range of different fuels and fuel mixtures. These fuels and/or mixtures each have corresponding properties heating values, specific gravities, methane numbers, etc.) that can vary greatly. If unaccounted for, an engine operating in a satisfactory manner using a first fuel, may not operate as desired (e.g., the engine may not meet emissions and/or power requirements) or at all when fed a second fuel. For example, the engine may not start when supplied with the second fuel using settings previously successful with the first fuel.
Conventionally, a fuel of unknown consist or quality is accommodated by way of testing. In particular, samples of the fuel are taken and lab-tested to determine the corresponding properties. These properties are then manually input to a controller of the engine, such that the controller can adjust engine settings based on the properties. In some situations, the engine settings are manually adjusted based on the lab-testing. While this approach may be somewhat successful, it may also be resource expensive and unable to keep up with unexpected fuel changes.
One attempt to address the above-described problems is disclosed in U.S. Patent Publication No. 2015/0090222 of Rebinsky that published on Apr. 2, 2015 (“the '222 publication”). Specifically, the '222 publication discloses an engine system equipped with a fuel quality sensor. The fuel quality sensor has a sensing element configured to sense at least one of a heat capacity and a thermal conductivity of an unknown mixture of gaseous fuel, and a heating element configured to increase a temperature of the unknown mixture to multiple different temperature levels during sensing. The fuel quality sensor also includes a microprocessor configured to calculate at least one of a lower heating value, a Wobbe index, a % diluents, a specific gravity, a specific heat ratio, and a methane number of the unknown mixture as a function of the heat capacity and/or the thermal conductivity sensed at the multiple different temperature levels. The engine system also includes a controller configured to selectively adjust at least one of an air/fuel ratio, a timing, or a load on the engine based on the lower heating value, the Wobbe index, the % diluents, the specific gravity, the specific heat ratio, and/or the methane number.
Although the method described in the '222 publication may be adequate in some applications, it may still be less than optimal. For example, the method relies on input from a fuel quality sensor that may only be operational during operation of the engine. Accordingly, the method may not be applicable to startup of the engine. In addition, because the sensor relies on heating of the gas to multiple different temperatures, the sensor may be slow. Further, use of the sensor may increase a cost and complexity of the engine system.
The disclosed engine system is directed to overcoming one or more of the problems set forth above.